channel or channelFactory not set&&Exception in thread "main" java.lang.IllegalStateException: childHandler not set
/以上错误,是在初始化ServerBootstrap这个类没有初始化channelFactory导致的。
ServerBootstrap继承了AbstractBootstrap这个类,其中ServerBootstrap.bind()的时候,其实是父类调用bind(),接着会调用validate()函数,而子类重写了validate()函数,这个函数中,先实现super.validate(),下面看一下父类中是如何实现validate的
@SuppressWarnings("unchecked") public B validate() { if (group == null) { throw new IllegalStateException("group not set"); } if (channelFactory == null) { throw new IllegalStateException("channel or channelFactory not set"); } return (B) this; }
这说明在这之前初始化了channelFactory,但是在哪里呢?我们接着:
/** * Create a new {@link Channel} and bind it. */ public ChannelFuture bind() { validate(); SocketAddress localAddress = this.localAddress; if (localAddress == null) { throw new IllegalStateException("localAddress not set"); } return doBind(localAddress); }
其中doBind()中有一个函数 initAndRegister()
final ChannelFuture initAndRegister() { final Channel channel = channelFactory().newChannel(); try { init(channel); } catch (Throwable t) { channel.unsafe().closeForcibly(); // as the Channel is not registered yet we need to force the usage of the GlobalEventExecutor return new DefaultChannelPromise(channel, GlobalEventExecutor.INSTANCE).setFailure(t); } ChannelFuture regFuture = group().register(channel); if (regFuture.cause() != null) { if (channel.isRegistered()) { channel.close(); } else { channel.unsafe().closeForcibly(); } } // If we are here and the promise is not failed, it's one of the following cases: // 1) If we attempted registration from the event loop, the registration has been completed at this point. // i.e. It's safe to attempt bind() or connect() now because the channel has been registered. // 2) If we attempted registration from the other thread, the registration request has been successfully // added to the event loop's task queue for later execution. // i.e. It's safe to attempt bind() or connect() now: // because bind() or connect() will be executed *after* the scheduled registration task is executed // because register(), bind(), and connect() are all bound to the same thread. return regFuture; }
channel()是初始化channelFactory的地方,其中有这么一个类:
public class ReflectiveChannelFactory<T extends Channel> implements ChannelFactory<T> { private final Class<? extends T> clazz; public ReflectiveChannelFactory(Class<? extends T> clazz) { if (clazz == null) { throw new NullPointerException("clazz"); } this.clazz = clazz; } @Override public T newChannel() { try { return clazz.newInstance(); } catch (Throwable t) { throw new ChannelException("Unable to create Channel from class " + clazz, t); } } @Override public String toString() { return StringUtil.simpleClassName(clazz) + ".class"; } }
validdate是需要初始化childHandler的用于后来ServerBootstrapAcceptor的初始化,一个InBoundAdapter @Override public ServerBootstrap validate() { super.validate(); if (childHandler == null) { throw new IllegalStateException("childHandler not set"); } if (childGroup == null) { logger.warn("childGroup is not set. Using parentGroup instead."); childGroup = group(); } return this; }